Elevator installations are incorporated in a building. They essentially consist of an elevator car connected by way of support cables or support belts with a counterweight. The car as well as the counterweight are moved along substantially vertical guide rails by means of a drive, which selectably acts on the support means, directly on the car or the counterweight. The elevator installation is used for conveying persons and goods within the building over individual or several floors.
The elevator installation includes devices in order to safeguard the elevator car in the case of failure of the drive or the support means or to protect against undesired drifting away or dropping down even in the case of a stop at a floor. For that purpose, use is usually made of safety brake devices which can in case of need brake the elevator car on the guide rails.
Until now, safety brake devices of that kind were activated by mechanical speed limiters. However, currently, increasing use is also made of electronic monitoring devices which can activate braking or safety brake devices when needed.
In order to nevertheless be able to have resort to known and proven safety brake devices, electromechanical actuating devices are required which in the case of appropriate control can actuate safety brake devices.
A device of that kind is known from EP 0543154. In that case, an auxiliary double-jaw brake is when required brought into engagement with a guide rail and this auxiliary double-jaw brake actuates an existing lever system, whereby safety brake devices are actuated. This auxiliary double-jaw brake is designed to be able to move the lever system and mass parts of the safety brake device. The requisite electromagnetic units have to be of correspondingly large size.
A further device of that kind is known from U.S. Pat. No. 7,575,099. In this solution, safety brake wedges of a safety brake device are directly actuated by springs when required. The springs are biased by an electromagnet and the biased springs are released when required. The springs can, if need be, be reset again by a spindle drive or stressed. This electromagnet also has to be of an appropriately large size, since the total biasing force of several springs has to be directly accepted and maintained.
Brake or safety brake devices are also often present at the counterweight in elevator installations. This is particularly the case when areas which can be walked on are present below the elevator shaft or when, for example, brake devices are needed at the counterweight in order to prevent uncontrolled upward movement.